This invention concerns a method and apparatus for making a gel plate with a microporous membrane for separating and transferring macromolecules by electrophoresis, the method and the apparatus utilizing a cassette with a rectangular frame and a removable bottom plate and into which the gel is poured in liquid form.
The applicant has already proposed a method and a manufacturing apparatus of that type, described in International Patent Application WO 93/01491, in which the gel in liquid form is first poured into the cassette until it is level with the top edge of the rectangular frame, after which a dry microporous membrane is laid progressively on to the gel and the frame, traction is applied to the periphery of the membrane to tension it in substantially uniform manner, and the gel is allowed to solidify while keeping the membrane tensioned.
That method and apparatus allow gel plates to be made with one face covered by an adhering microporous membrane, generally of nitrocellulose or nylon, satisfying a number of criteria, such as the homogeneity of the gel, uniformity of its thickness, absence of air bubbles between the gel and the membrane, flatness of the membrane and cleanness of its free face.
That method and apparatus also make it possible to avoid some problems with the prior art, such as the gel overflowing onto the free face of the membrane and the formation of folds in the membrane, resulting from its elongation during its impregnation by the gel, which problems are generally encountered when the liquid gel is poured onto the membrane placed on a support.